CAMEL-23572: camel-tui: Add documentation viewer and README support

[davsclaus]

Summary

• Include README files (.md, .adoc) when running integrations via camel run, tracked via camel.jbang.readmeFiles property and exposed in status JSON
• Add Show Documentation to the F2 actions menu — lists running integrations with README files, fetches content via the new readme action, and renders with TamboUI's MarkdownView widget
• Add d key in the example browser to view README docs for any example: bundled examples load from JAR resources, online examples download from GitHub (tries .md first, falls back to .adoc)
• Convert all bundled example READMEs from AsciiDoc to Markdown for proper rendering
• Include AsciiDoc-to-Markdown converter (DocHelper) for online .adoc fallback
• Auto-select first row in circuit breaker tab when switching to it

Test plan

• Run camel run with an example that has a README file, verify the README is included via camel get status
• Open TUI (camel monitor), press F2 → "Show Documentation" → verify running integrations with READMEs are listed
• Select an integration from the doc picker → verify README content renders in MarkdownView
• Press F2 → "Run an example" → select a bundled example → press d → verify README displays
• Press d on an online example → verify README downloads and displays
• Press Esc in doc viewer opened from example browser → verify it returns to example browser
• Press 9 for circuit breaker tab with data → verify first row is auto-selected
• Verify AsciiDoc content (headings, code blocks, links) renders cleanly through the converter

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